First Results of Cavitation Erosion Behavior of Plasma Nitrided Niobium: Surface Modification

This work presents the first results of the plasma nitriding study performed in pure niobium in order to increase its cavitation erosion resistance. Samples were prepared from 98.9% purity and 90% reduction cold-rolled niobium bars. Annealing treatment of the cold-worked niobium samples was carried out in vacuum furnace at 1.33 Pa pressure, in the temperature of 1000 °C, for a time of 60 min. Annealed samples showing hardness of 80 HV were cut to dimensions of 20 × 30 × 4 mm3. Nitriding treatment was conducted at 1080 °C, gas mixture of 90% N2 + 10% H2, flow rate of 5 × 10–6 Nm3s–1, a...